That's an simple use of rules... look in your Mail prefs to add a rule.
If you just need to sort your mailbox, and not send to other mailboxes, then just click on the 'From' header, which immediately sorts by 'from' address.
Dahh... Thanks. I've used rules and the "From" address before but just didn't think about it.
One thing I did in the mean time is set up a smart box for the past week.
The other problem with "From" is the same guy from the same address can show up in two places. Sometimes the From will have his name and other times it will just be his email address. I'm not sure how to deal with that.